This invention relates to an apparatus for selectively magnifying or shielding the viewfinder image of a camera.
In order to observe a viewfinder image with a camera held at waist level through a typical penta prism viewfinder optical system of a single lens reflex camera, an angle finder must be connected to the viewfinder eye piece to enable sighting from above. Where close-up photography or accurate focusing is involved, on the other hand, a magnifier is attached to the eye piece, and after the visual field of the magnifier is suitably set, the camera lens is adjusted to accurately bring the object into focus. When this is done through a magnifier, whose magnification is generally on the order of 1.5 to 3, only a central portion of the finder image is observed through the magnifier. That is, it is impossible to observe the entire photographic field seen by the viewfinder. Therefore, after a photographic composition has been determined by visually observing the field through an angle finder, the latter must be disconnected from the viewfinder eye piece and the magnifier connected thereto to accurately focus the object. During such exchange, however, the composition of the object may vary, and therefore it may be necessary to readjust both the composition and the focus. Such alternate use of an angle finder and a magnifier is obviously troublesome.
Further, in self-timed or multiple copy photography using an SLR camera having an automatic exposure control system and TTL metering, it is impossible to photograph the object with the operator's eye on the eye piece of the angle finder, whereby reverse incident light may enter the camera through the eye piece and adversely affect the exposure value.